We're trying to perform some tests in UCM, but we're not finding many examples about it.
This is what we want to do:

We want to use webservices to checkin files to UCM.

How?

1 - we will develop a java application
2 - inside the application there will be a button that will call the webservice
3 - after the webservice is called, the document should go to out UCM

Until now, I'm doing only research. Reading documents about webservices, how they work and everything I managed to find.
But I can't find an example about it. Someone, please, could say where I can find it?

I've managed to create a simple WS (Hello World) using a WSDL. The guide is found at:
http://www.roseindia.net/webservices/buildingsimplewebservice.shtml

It's working OK.

Now we're trying to use the Check-in WSDL of our UCM. We downloaded it, added to the project but we don't know how to call it.
This is our project:
http://imgur.com/OCHsz

I could not find any guides teaching me how to call the WS, or how to pass the metadata parameters (they are necessary) to do a successful check-in.
Anyone, please, could guide/teach me on how to do it or where I can find the info?
I'm a newcomer in this WS/UCM world and I'm asking everyone about it, even our Java consultants don't have all the knowledge about it.
Thanks all!

as for the UCM piece, check this link out: http://docs.oracle.com/cd/E23943_01/doc.1111/e10807/c25_wsdl_and_soap.htm#BEHHIGHJ
It describes what service with what parameters should be called. There are also SOAP Request and Response schemes.

If I understood your question, it is more how to create a piece of code that calls the service, right? This very much depends on what your programming language is, and partially also what your IDE is. There is a comprehensive tutorial for Java/Jdeveloper available here: http://st-curriculum.oracle.com/obe/jdev/obe11jdev/ps1/webservices/ws.html I believe if you go through that you will be at least a journeyman on WS. Another good resources can be found http://www.ibm.com/developerworks/webservices/library/ws-javaclient/ or http://qnatech.wordpress.com/2008/07/29/how-to-write-code-to-invoke-a-web-service-from-java/

The problem is exactly what you've said: "... it is more how to create a piece of code that calls the service, right?". I don't know how exactly code the call. We're using Java, in Eclipse.
I'm using your tutorials, let's see what happens.

I'm trying to replicate the scenario. I got stuck with check-in services (CheckIn.wsdl has some conflict in JDev, probably with one of installed components), so will try to post a sample with other services.

Note that with those IDEs, it usually fills parameters for you - you just need to provide the right XMLs. I'll try to get something working and come back.